Necessary to ground and XLR interconnect?

You will get potential for hum if you don't run the shield through - normally pin 1 is ground connect the shield to here both ends. Pin 2 is positive and pin 3 is negative - nothing to do with ground :-) and remember to take a close look at those small numbers 1 and 2 are reversed in relation to 3 from the male to the female XLR

Good luck

Peter

Pbnaudio has it, that's the point of XLR. With three conductor XLR cables/inputs/outputs, the shield of the cable, designed to pick up all the stray RF and EM noise around the cable, isn't inserted into audio inputs. The shield protects the positive and negative audio signal.

Brad

With XLR signal connection/connectors, there are two possible "grounds". Signal ground and chassis ground.

Pin 1 is 'signal ground' and is the zero (0) signal reference point between pin 2(+) and pin 3(--). There is also a (fourth) connection point on the case, or barrel, of the XLR connector which is 'chassis' ground. It may or may not be the same as 'signal' ground, depending on the design of the circuit/component in question; often the 'balanced' connections in audio gear are really only pseudo-balanced; which is to say they are really two identical single ended signals, a 'hot' and a 'common' (or chassis ground) where one of the single ended signals has had its polarity inverted (the 'hot' is changed in polarity from + to --) and then it is re-combined with the non-inverted single ended signal to make a "kind of" balanced signal (which can then drive a balanced input on another component.) But it's not a true balanced output.

However, if you want to shield the signal conductors (in a balanced cable), it's best IMO to use 'chassis' ground, and connect the shield (at both ends) to the barrel of the XLR connectors. There is no need to 'float' the shield (connect it at only one end) with balanced interconnects, since there's no chance for any current that might develop in the shield to find its way into the signal path.

Just my two cents.
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Thanks-so I should connect a shield to both ground pins, not one. But if I don't want to use a metal foil/braid shield, should I connect up the ground pins with a wire anyway, or would there be no point to that? My shield will be a non-metallic outer covering--Flexo Conductive carbonized braid.